This is a bad move, but I call the reader's attention to Arjun's style. He's not afraid of taking big risks to play for a win. Sometimes this comes with a few mistakes, but it also makes the position hard to play for his opponent.
21. e5f6 White cedes the bishop pair for a good cause: damaging the kingside and creating threats around the black king. 21... g7f6  22. d1h5  22... g8f8  23. c2b3 Up to now, this is a tense and well-played game. The position remains very complicated, and we will see a few mistakes in the remainder of the game.